It is known to provide permanently fixed dentures which include implants anchored in the mandible or maxilla osseous portions and a denture including an artificial gum and teeth structure being fixed to the implants and/or existing teeth or roots.
It is also known to provide a bridge or denture which includes a locking device adapted to lock onto the crown of a tooth. However, the torque which can be produced by the denture on the tooth or teeth by the function of the prosthesis can damage the crown of the tooth and render it useless.
It is also known to have a denture which is removably detached from an implant structure, wherein the implant structure includes a metallic arch or bar formed to bridge individual roots or root substitutes, such as pins implanted directly into the osseous material of the mandible or maxilla. The denture includes an artificial gum structure adapted to fit snugly over the arch and locking device for locking the denture to the arch. An example of such a device is described in U.S. Pat. No. 4,085,506, issued Apr. 25, 1978 to Isaih Lew. Such an assembly requires the arch to accommodate the locking device.
U.S. Pat. No. 5,716,214, granted on Feb. 10, 1998 to Lund et al., describes a dental prosthesis system in which a denture is removably secured to a mandible having permanent osseous implants. The interconnection between the denture and the implant is achieved by male/female members, that are releasable from one another when it is desired to remove the denture from the mandible. A single surface of interference is provided between the male and female members, so as to retain the denture onto the mandible. Moreover, the interference between male and female member is effected by a pair of arcuate surfaces, and maintained by a spring.
Because of the pressures exerted during chewing (i.e., high magnitude, from any direction), it is believed that denture attachment systems having single surfaces of interference may be subjected to the undesired detachment of the denture from the mandible. Moreover, in the system of U.S. Pat. No. 5,716,214, the pressures exerted on the denture are potentially transmitted against the biasing action of the spring because of the contact between the arcuate surfaces of the male and female members. This may ultimately lead to the disconnection of the denture from the implant.